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OVERVIEW OFTHE SOUTH KOREA TRANSMISSION NETWORK
( with particular emphasis on the recently commissioned 765kV Network )
KOREA ELECTRIC POWER RESEARCH INSTITUTE
T. I. Jang*, D. I. Lee*, G. J. Jung*, J. S. Ahn*, J. Y. Koo**
*KEPRI, **Hanyang University
2345 & 765kV Transmission Lines of Korea
1st Project
2nd Project
3rd Project
345kV T/L
3AGENDA
Overview of Korea Power Statistics
Introduction of Korea 765 kV System
• Load
• Generation
• Transmission Lines
• Substation
• Transmission Lines
• Substation
4Load Trends of Korea
Item Year 1999 2000 2001 2002
Energy Sales [GWh] 214,215 239,535 257,731 278,451
Increase per annum [%] 10.7 11.8 7.6 8.0
Peak Load [MW] 37,293 41,007 43,125 45,773
Increase per annum [%] 13.0 9.9 5.2 6.1
Consumption per capita [kWh] 4,572 5,067 5,444 5,845
Increase per annum [%] 9.7 10.8 7.4 7.4
Energy Sales [GWh]Energy Sales [GWh] Peak Load [MW]Peak Load [MW] Comsumption per capita [kMh]Comsumption per capita [kMh]
5Trend of Generating Facility
Total : 53,801 [MW](2002)
Total : 53,801 [MW](2002)
Thermal : 63.6% Thermal : 63.6%
Nuclear : 29.2%Nuclear : 29.2%
Hydro : 7.2%Hydro : 7.2%
6Trend of Transmission Line Length
Total : 27,937 [c-km](2002)
Total : 27,937 [c-km](2002)
154kV : 65.0%154kV : 65.0%
345kV : 26.8%345kV : 26.8%
Below 66kV : 5.0%Below 66kV : 5.0%
765kV : 2.4%765kV : 2.4%
DC ± 180kV : 0.8%DC ± 180kV : 0.8%
7Trend of Capacity of Transformer
Total : 160,838 [MVA](2002)
Total : 160,838 [MVA](2002)
154kV : 51.9% 154kV : 51.9%
345kV : 42.9%345kV : 42.9%
765kV : 4.4%765kV : 4.4%
Below 66kV : 0.8%Below 66kV : 0.8%
8
Transmission Lines: 330 km (1st Project)
• Conductor : ACSR 480 mm2 × 6 Bundles• Ground Wire : AW 200 mm2, OPGW 200 mm2
• Switching Surge : 1.9 p.u. & TOV : 1.2 p.u.• Tower Foundation : pad & chimney, pier etc.• Tower Design
- Type: Pipe - Span: 500~600 m- Height: 80~100 m - Weight: 70~100 tons
• Insulator String : 300 kN, 400 kN, 530 kN
Substation: 4 substations (1st Project)• Type: outdoor GIS• BUS Scheme: 2 BUS 1.5 CB• 765 kV 8 T/L, 4 Transformer Bank (or 5 Bank)• Site Area: approximately 235,000 m2
• Transformer: 1 Ph, 666 MVA × 3 (765/345/23 kV)- BIL: 2,050 kV - Weight: 150 tons
• Circuit Breaker: rated current 8 kA- BIL: 2,250 kV - Short Circuit Cap.: 50 kA
Overview of 765kV Facilities
9
Necessities
• Increasing Rate of Peak Demand : average 10 % / year
• Difficulty of Obtaining on Rights-of-way
Upgrading Advantage (765kV : 345kV)• Increasing of Transmission Capacity
1,800,000kW 8,400,000kW
4.7 times of 345kV
345 kV345 kV 765 kV765 kV
Characteristics of Korea 765kV Upgrading
10
• Decreasing of Transmission Loss : 20 % of 345 kV
• Decreasing of Tower Area : 50%
• Decreasing of Transmission Line Route Area : 30 %
53% of 345kV
11Conductor
Cross sectional view of wiresCross sectional view of wires 6 bundle conductor and spacer6 bundle conductor and spacer
Kind of Conductor
Stranded wire composition
Calculated sectional
(mm2)
Tensile strength
(kg)
Outer diameter
(mm)
Weight(kg/km)
Coefficient of elasticity
Coefficient of linear expansion(106 / °C)
ACSR 480mm2
(Cardinal)Al 54/3.38St 7/3.38
Al 484.53St 62.81
15,300 30.42 1,836 7,987 19.53
12Ground Wire & Jumper of Tension Tower
JumperJumper
Ground WireGround Wire
AW 200mm2 and OPGW
200mm2
Suspension rod type pre-fab Jumper
13Insulator Strings and Fittings
No. Name of Parts
1 Tower Fitting
2 90° Clevis Eye
3 Yoke
4 Ball Clevis
5 Arcing Horn
6 Insulators
7 Arcing Ring
8 Socket Clevis
9 Yoke
10 90° Clevis Eye
11 Eye Link
12 Clevis Eye
13 Suspension Clamp
14 Yoke
15 90° Clevis Eye
16 Eye Link
17 90° Clevis Clevis
14
The Number of Insulators of KEPCO 765 kV Transmission Line
Sea Level
Pollution LevelClean Polluted Area
Clean I Clean II A B C D
ESDD(mg/cm2)
~ 0.01 ~ 0.03 ~ 0.063 ~ 0.125 ~ 0.25 ~ 0.5
Type Normal type Fog type
Below 1,000m
SUS
300kN 30 37 44 34 39 45 50
400kN 29 36 41 33 38 45 50
TEN
400kN 28 36 41 33 38 45 50
530kN 24 30 35 - - - -
15
Kinds of Insulator String
• Suspension String : 300 kN × 2, 400 kN × 2• V Suspension String for Jumper : 210 kN × 2• Tension String : 400 kN × 3
Impulse test of suspension insulatorImpulse test of suspension insulator Arc-resistivity test of arcing hornArc-resistivity test of arcing horn
16Typical 765 kV Transmission Tower
Suspension TypeSuspension Type Tension TypeTension Type
17Tower Design
Manufacturing of 765 kV tubular towerManufacturing of 765 kV tubular tower
• Kind of members : pipe (arm part is angle)
• Tower Type- Type: A, LA, B, C, D, D0, X (dead end tower)
- C type and above (heavy angle tower): asymmetric arm - Inside arm is shorter than the outside arm
• Accessories : Ladder, Rail for Lift, Resting places etc.
Lift for tower and its railLift for tower and its rail
18Foundation Design
Ordinary foundation• pier & pad foundation, pier foundation, rock anchor foundation
Special foundation• pile foundation, well foundation
Pier foundationPier foundation
Excavation of pier foundation using
Telescopic
Excavation of pier foundation using
Telescopic
Setting the stubSetting the stub
19Design of Ground Clearance
• Electric Field on ground level = 3.5 kV/m (resident area) 7.0 kV/m (mountain area)
DivisionFacility standard
(m)
Added value(m)
Designed value Remarks
Flat ground area 13.68 - 28 Region frequented by people
Mountainous area 12.68 - 19Region seldom visited by people
and with no tree
Railway(Including electric railway)
14.18 - 28
Road 13.68 - 28Express highway, national road
and other
Other trees 10.88 16.2 27
Larches 10.88 21.2 32 Collective afforestation area
Rigid Pine trees, Big cone pines 10.88 21.2 32 Collective afforestation area
Farm land 13.68 - 28
Scheduled residential area (3 stories) 10.88 - 28
Other structures crossing separating 10.88 4 15Overhead electric wires,
Overhead low voltage line
20Electrical Environment Design
Test Results from long term tests for 28 months
Cardinal Conductor (480mm2 x 6 Bundle / Phase) satisfies
the KEPCO design Criteria
Cardinal Conductor (480mm2 x 6 Bundle / Phase) satisfies
the KEPCO design Criteria
ITEM Test Results Criteria
AN• Rainy weather: 48.4 dB(A)• Fair weather: 40.9 dB(A)
50 dB(A)
RI• Fair weather: 43.5 (dBµV/m) = SNR 25.7 dB
SNR 24 dB
TVI• Rainy weather: 14.2 (dBµV/m) ≈ SNR 40 dB
SNR 40 dB
21Insulation Design
Overvoltage Analysis Results
• Power Frequency Temporary Overvoltage is below 1.2 p.u.
- 1.2 p.u. (analysis results) + margin = 1.2 p.u.
• Line-to-Ground Fault Initiation is below 1.8 p.u.
- No Reduction Method
• Energization & Re-energization with one step per-insertion resistor is below 1.9 p.u.
- Maximum Resistor Value 800 Ohms (Optimum = 400 Ohms)
• Simultaneous Single Line-to-Ground Fault Clearing at each circuit is below 1.9 p.u.
- Without Opening Resistor
22
Lighting Flashover Rate
• Calculated Condition
- IKL : 20
- Shielding Angle : -8 degree
- Hill Side Angle : 10 degree (average)
- Tower Foot Resistance : 15 ohms
- Horn Gap Length : 4.6 m, 4.8 m (765 kV)
2.34 m (345 kV)
Shielding AngleShielding Angle
Ground wire arm is longer than lower arm by 1 m and
shielding angle of upper conductor is approximately –8 degrees.
Ground wire arm is longer than lower arm by 1 m and
shielding angle of upper conductor is approximately –8 degrees.
23Type of substation
Type : Outdoor Full GIS Type
• With no exposure of hot-line parts, except for the bushing at the front end of incoming T/L
• Most equipment is installed inside a metal enclosure which is insulated with SF6 gas
• GIS and Transformer are connected with a SF6 Gas Insulated Bus (GIB)
BUS Scheme : Double Bus 1.5CBs Type
• Highly reliable (in case of bus failure), flexible (in power flows) and economical
• Enough operational experience with this type:
- The standard bus scheme in the 345 kV S/S
24View of 765 kV Substation
765kV Sin Ansung S/S765kV Sin Ansung S/S
25Completed 765kV Commercial T/L
26Completed 765kV Commercial T/L
27
Basic Concept
• External over voltage: Suitable arrangement of high performance surge arrester
• Internal over voltage: No flash over
Internal over voltage criteria
Standard Insulation Distance
DivisionOvervoltage Ratio
(p.u.)p.u. Ratio
Power Frequency Overvoltage
Phase conductor 1.21 p.u. = kV
Neutral 0.3
Switching Overvoltage
Phase to ground 1.81 p.u. = 800 × kV
Phase to phase 3.5 3
2
3
800
Insulation Clearance Standard Minimum
Phase to Phase 11 m 8.5 m
Phase to Ground 7 m 5 m
Insulation Design
28
• 2 tanks for each phase: possibility of transportation
• It is possible to operate 1 tank for each phase
Classification Rating
Type Auto transformer (2 tanks per each phase)
Rated voltage 765 / kV, 345 / kV, 23 kV
Capacity (1, 2) 2,000 / 3 MVA
Capacity (3) 60 / 3 MVA
Tap range ± 7 % (23 tap)
% Impedance 18 % (1st-2nd wire)
Cooling 3 steps FOA (ANSI)
Audible noise 85 dB
3 3
Main Power Transformer
29Setting the Main Transformer in Sin Ansung S/S
30800 kV GIS at Sinseosan S/S
31
• On-line diagnosis of the operating status of apparatuses• Use accumulated data to prepare an optimal maintenance and repair plan according to the condition of devices
MTr.
DAS
GIS
DASCCU
ClientServer
HUB
Printer Server
To Control system
Optical LAN
765 kV Predictive diagnostic system configuration765 kV Predictive diagnostic system configurationClass Diagnose Item
MTr.
• Gas in oil• Temperature• Oil level• particle Discharge• OLTC• Fan, pump current• Current and voltage• Ambient temperature
GIS
• UHF Coupler• CB, HSGS operation• Gas pressure• LA current
Preventive Diagnostic System
32
• Full GIS type• Colored water-permeable concrete at the switch yard surface• A barrier of trees on the outside• Application of 3D graphic simulation
Bird’s eye viewBird’s eye view 3D graphic simulation3D graphic simulation
Environmental Countermeasures
33Conclusions
765kV Transmission Line of Korea is the first 765kV double circuit AC T/L
in the world
• Bulk Carrying Capacity ( 8,400 MW ): 5 times of 345 kV
• Efficient Utilization for Land ( 529 m2): 53% of 345 kV
• Cost Reduction in Construction ( 3,900 million Won/km ): 74% of 345 kV per kW
• Decrease in Transmission Loss ( 0.05% ): 20% of 345 kV
• Environment Affinity 765 kV Transmission Line: EMF, Corona
Characteristics of 765kV Transmission Lines
Exporting of Technology
• Vietnam, Myanmar, Libya, China, etc.
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